sam460ex: Make sam460ex_load_device_tree() handle all errors internally

sam460ex_load_device_tree() handles nearly all possible errors by simply
exiting (within helper functions and macros).  It handles two early error
cases by returning an error.

There's no particular point to this, so make it handle those directly as
well, removing the need for the caller to handle a failure.  As a bonus it
gives us more specific error messages.
Signed-off-by: NDavid Gibson <david@gibson.dropbear.id.au>

hw/ppc/sam460ex.c

@@ -255,7 +255,6 @@ static int sam460ex_load_device_tree(hwaddr addr,
                                      hwaddr initrd_size,
                                      const char *kernel_cmdline)
 {
-    int ret = -1;
     uint32_t mem_reg_property[] = { 0, 0, cpu_to_be32(ramsize) };
     char *filename;
     int fdt_size;
@@ -266,12 +265,14 @@ static int sam460ex_load_device_tree(hwaddr addr,
 
     filename = qemu_find_file(QEMU_FILE_TYPE_BIOS, BINARY_DEVICE_TREE_FILE);
     if (!filename) {
-        goto out;
+        error_report("Couldn't find dtb file `%s'", BINARY_DEVICE_TREE_FILE);
+        exit(1);
     }
     fdt = load_device_tree(filename, &fdt_size);
     g_free(filename);
-    if (fdt == NULL) {
-        goto out;
+    if (!fdt) {
+        error_report("Couldn't load dtb file `%s'", filename);
+        exit(1);
     }
 
     /* Manipulate device tree in memory. */
@@ -325,11 +326,8 @@ static int sam460ex_load_device_tree(hwaddr addr,
 
     rom_add_blob_fixed(BINARY_DEVICE_TREE_FILE, fdt, fdt_size, addr);
     g_free(fdt);
-    ret = fdt_size;
-
-out:
 
-    return ret;
+    return fdt_size;
 }
 
 /* Create reset TLB entries for BookE, mapping only the flash memory.  */
@@ -599,10 +597,6 @@ static void sam460ex_init(MachineState *machine)
         dt_size = sam460ex_load_device_tree(FDT_ADDR, machine->ram_size,
                                     RAMDISK_ADDR, initrd_size,
                                     machine->kernel_cmdline);
-        if (dt_size < 0) {
-            error_report("couldn't load device tree");
-            exit(1);
-        }
 
         boot_info->dt_base = FDT_ADDR;
         boot_info->dt_size = dt_size;